There are three types of damage in OSR+: lethal damage, subdual damage, and attribute damage. If the source of damage does not specify otherwise, then the source deals lethal damage.
Lethal Damage
Lethal damage is the sort of damage that can affect armor points (AP), hit points (HP), and deliver wounds. Lethal damage can put you on death's door.
Illusory Damage
Damage dealt by illusions is considered a special type of lethal damage. Illusory damage is real to those who fail to disbelieve the illusion, and so their body reacts accordingly. Treat illusory damage exactly the same as you would lethal damage: it can inflict wounds, and it can put you on death's door. And yes, you can even die from illusory damage.
If you're on death's door and nobody stabilizes you by breaking the illusion, you die.
Once you disbelieve an illusion however, any damage it has caused is immediately recovered. (But this is not the case if you’re dead!)
Subdual Damage
Subdual damage is non-lethal damage. You can choose to deal subdual damage instead of lethal damage with any weapon or maleficence, provided you declare the type of damage before making the attack roll. (In the fiction, you might be using the butt of your gun or the hilt of your sword to strike an opponent, for example.) Subdual damage recovers at a rate of 1 HP per hour. Subdual damage can knock you unconscious, but does not put you on death's door. Wounds from subdual damage recover like HP and do not confer a -1 penalty to all your actions.
Attribute Damage
When you suffer attribute damage, your attribute is reduced by the amount of damage you receive. The source of the damage will indicate what attribute is reduced. You do not recalculate any other scores when your attributes are reduced (for example, if you lose Mighty or Deft, you do not recalculate your HP or defense). However:
- At 0 Smart, you cannot cast spells.
- If a relevant attribute is reduced to 0, you do not gain a +2 from any skills relevant to it, nor can you use weapon tactics that rely on that attribute.
- If your Mighty is reduced to a score that is less than your armor's Mighty requirement, you lose the benefit of its AP and soak, and so on.
If all your attributes are reduced to 0, you are put on death's door. Only by recovering at least 1 attribute point of damage can you be stabilized when on death's door with 0 in all attributes.
Attribute damage cannot be recovered except by spells like Restore or Remove Curse, or magical consumables like a Potion of Restoration.